and Design Chapter 12 Principles File Management

Chapter 12 File Management Eighth Edition By William Stallings Operating Systems: Internals and Design Principles Files data collections created by users The File System is one of the most important parts of the OS to a user Desirable properties of files: Long-term existence files are stored on disk or other secondary storage and do not disappear when a user logs off Sharable between processes files have names and can have associated access permissions that permit controlled sharing Structure files can be organized into hierarchical or more complex structure to reflect the relationships among files File Systems Provide a means to store data organized as files as well as a collection of functions that can be performed on files Maintain a set of attributes associated with the file Typical operations include: Create Delete Open Close Read Write File Structure Four terms are commonly used when discussing files: Field Record File Database Structure Terms Field basic element of data contains a single value fixed or variable length File collection of related fields that can be treated as a unit by some application program fixed or variable length Record Database collection of similar records treated as a single entity may be referenced by name access control restrictions usually apply at the file level collection of relat

File Management System Objectives Meet the data management needs of the user Guarantee that the data in the file are valid Optimize performance Provide I/O support for a variety of storage device types Minimize the potential for lost or destroyed data Provide a standardized set of I/O interface routines to user processes Provide I/O support for multiple users in the case of multiple-

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  Principles, Management, Data, Data management

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